qemu-img: Make create hint at protocol options

qemu-img create allows giving just a format and "-o help" to get a list
of the options supported by that format.  Users may not realize that the
protocol level may offer even more options, which they only get to see
by specifying a filename.

This patch adds a note to hint at that fact.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/qemu-img.c b/qemu-img.c
index d7fe546..ddd55ab 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -267,9 +267,20 @@ static int print_block_option_help(const char *filename, const char *fmt)
         create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
     }
 
-    printf("Supported options:\n");
+    if (filename) {
+        printf("Supported options:\n");
+    } else {
+        printf("Supported %s options:\n", fmt);
+    }
     qemu_opts_print_help(create_opts, false);
     qemu_opts_free(create_opts);
+
+    if (!filename) {
+        printf("\n"
+               "The protocol level may support further options.\n"
+               "Specify the target filename to include those options.\n");
+    }
+
     return 0;
 }